Spectra of different light beams have different hues. Therefore, an object develops different visual perceptions while the object is being irradiated by light sources with different spectra. For instance, while the object is being irradiated by a light beam with a reddish spectrum, the light beam casts a warm hue on the object; while the object is being irradiated by a light beam with a bluish spectrum, the light beam casts a cold hue on the object. In terms of commercial applications, the visual perception developed by the object poses an impact on consumers' desires to shop. The spectrum of the light source, if properly modulated according to design demands, can create experiences which influence consumers' mood as well as stimulate the shopping behavior.